Collaborative Paper Published: Thermally Triggered Non-Diffuse Phonon Reflection from Boundaries in Single-Crystal Diamond Nanobeams

Summary

In this paper, we demonstrate the possibility of modulating phonon reflection at the boundaries of single-crystal diamond nanobeams by using temperature as a control parameter. Thermal conductivity measurements from room temperature down to ~140 K show that the thermal conductivity decreases monotonically with decreasing temperature, whereas the results increasingly and systematically deviate at lower temperatures from a “fully diffusive boundary scattering” model based on first-principles calculations and the Boltzmann transport equation. By analyzing this discrepancy, we reveal that the contribution of specular phonon–boundary scattering becomes more significant in the low-temperature regime, and that its temperature sensitivity is larger in diamond than in silicon. This work is a collaborative research outcome with the group of Associate Professor Park at Hanyang University.